i actually have once, i had a ruler designed guy up in the frozen hored, he was just some plain nord with dragon cult religion. yeah i was living up there hapily having tons of children, had like 30 or so i think lost count at age 40 lol. and when my old king nord guy was like 70 years old, i just got the dragonborn trait, and all my chldren got the descendant trait. i think it might have extended my nords life because he lived till he was 130 untill he died of an infected wound. i dont know how i bacame, probly just the random chance when the current one died.